1. Field of the Invention
The present invention relates to decalcomania art, i.e., the art of transferring pictures and designs from specially prepared substrates to other surfaces, such as cloth garments. More specifically, this invention is directed to a method and apparatus for making improved heat transfers of flocking material, and to the flocked heat transfers made thereby.
2. Description of the Prior Art
A conventional method of making "heat transfers" of flocking material is disclosed in U.S. Pat. No. 3,379,604, issued to Webber, et al. A "heat transfer" as used in the decalcomania art, refers to a heat transferable design or decorative pattern, specifically formed on a paper or cloth substrate. Sometimes, it is referred to as a "dry transfer decalcomania". Flocking material, of course, is finely divided particles of fabric, such as wool, rayon, nylon, etc.
To make a flocked heat transfer by the process disclosed in the above-mentioned Webber et al patent, a heat-curable adhesive material is applied to the surface of a thermoplastic film in the form of a desired pattern. Thereafter, flocking material is selectively applied to the adhesive to form a flocked pattern. An open mesh carrier cloth is then placed over the flocked pattern and its thermoplastic support, and heat and pressure are applied simultaneously. The heat suffices to soften the thermoplastic film but not to permanently cure the flocked adhesive; the pressure aids in bonding the softened thermoplastic film to the cloth sheet. The resulting transfer is a sandwich structure which is 4 layers thick in the region of the flocked pattern, such layers being the cloth sheet, the flocking material, the uncured adhesive and the thermoplastic film. In the surrounding background areas, such sandwich structure consists only of the carrier cloth and the thermoplastic film. To transfer the flocked pattern from the carrier cloth to the fabric or garment receiving surface, such surfaces brought into contact with the flocked-bearing surface of the carrier cloth and heat and pressure are again applied. This time, however, the heat is sufficient to cure the adhesive and thereby permanently bond the flocked pattern to the receiving surface. The open mesh carrier cloth can then be peeled away, thereby exposing the flocked pattern.
In utilizing flocked heat transfers produced by the above process, it has been found that an undesired film of thermoplastic material is transferred to the ultimate fabric or garment receiving surface along with the flocked pattern. This undesired film appears in the background area of the flocked pattern and is, in fact, a portion of the thermoplastic film on which the flocked pattern was originally formed. In order to avoid the appearance of this objectionable film or deposit, it has been found necessary to accurately control, during the transfer operation, the temperature of the heat source the applied pressure, and the dwell time. If any of these parameters is excessive, the thermoplastic surface of the heat transfer will be softened to the extent that a substantial portion of the thermoplastic film will be re-transferred to the receiving surface. If any of the above parameters is below the level required for curing the flock adhesive, a poor transfer of the flocked pattern will result. The optimum temperature, pressure and dwell time for transferring the flocked pattern depends upon the curing temperature of the flocked adhesive, as well as on certain characteristics of the receiving surface. Inasmuch as many flocked heat transfers are utilized by individuals who not only have no knowledge of the optimum parameters for transfer, but also have no means for accurately controlling such parameters even if they were known, many heat transfers are used with less than optimum results.